The present invention relates to a method of winding a secondary coil of an engine igniting coil device.
Japanese laid-open patent No.60-107813 discloses a bank winding method applied for manufacturing a secondary coil of a compact engine ignition coil device having a necessary dielectric strength of the coil interlayer insulation. According to this bank winding method, an element wire being fed from a nozzle reciprocating in the coil winding direction for a distance of a specified width is suitably tensioned and wound spirally in banks of turns one by one in both forward and backward directions on the bobbin rotating by being driven by a driving shaft to which the bobbin is coaxially connected.
The conventional bank winding method, however, involves a problem that winding an element wire in layers in both directions on the coil bobbin may cause slip-down of wire turns resulting in collapse of windings.